[client] mouse: dont leave the window if any mouse buttons are held

client/src/main.h

@@ -226,6 +226,9 @@ struct CursorState
   /* the local position */
   struct DoublePoint pos;
 
+  /* the button state */
+  unsigned int buttons;
+
   /* the delta since last warp when in auto capture mode */
   struct DoublePoint delta;